1. Field of the Invention
The invention relates to a comb filter arrangement comprising a delay circuit and a first matching circuit having at least two storage cells, these circuits receiving a picture signal comprising a sequence of individual pixels applied to the comb filter arrangement and whose output signals are superposed by means of a superposition stage supplying a filtered picture signal from its output, the matching circuit being implemented in such a way that it gives the picture signal applied thereto substantially the same amplitude variations as the delay circuit, and that the difference between the delay of the output signals from the delay circuit and those from the matching circuit corresponds to a nominal value.
2. Description of the Related Art
Such comb filter arrangements are used in television receivers or video recorders. Glass fiber delay lines or CCD cells (Charge-Coupled Devices) are used as delay circuits for this purpose.
For an even further improved picture quality and a more precise processing of the picture signal, it is often desirable to switch such comb filter arrangements on and off temporally or, ideally, pixel-sequentially. However, the known comb filter arrangements are not suitable for this purpose, because the mode of operation of a delay circuit does not render it possible to switch it off, or because an amplification error results at the output of the comb filter arrangement when the delay circuit is switched off, as only the signal supplied by the matching circuit is applied to the superposition stage when the delay circuit is switched off. Consequently, amplitude and amplification errors are produced in those signal components which are supplied by the matching circuit and the delay circuit, and are normally superposed at the same phase.